A French Riviera cafe has created a stir on social media by rewarding its customers for good manners. At the Petite Syrah in Nice on the Cote d’Azur a cup of coffee becomes cheaper by adding a simple “Hello” and “please” when ordering. A blackboard outside the cafe advertises “Un cafe” for seven euros (£5.90; $9.6) – but “Bonjour, un cafe, s’il vous plait” costs just 1.40 euros. Owner Fabrice Pepino says it started as joke but his clients now smile more. A picture of the menu tweeted by a local journalist has gone viral. So far, the story on…